Fixation of a wiper system

ABSTRACT

The invention starts with a fastening of a wiper system ( 10 ) to a vehicle body ( 20 ) by means of a rubber elastic fastening element ( 22 ), which sits on the circumference in a receptacle opening ( 26 ) of the wiper system ( 10 ) or the vehicle body ( 20 ) and sits with a passage opening ( 28 ) on a pin ( 32 ) of the respective other part, whereby the connection between the wiper system ( 10 ) and the vehicle body ( 20 ) is detachable via a defined axial force ( 30 ) in the direction of the interior of the vehicle body ( 20 ). It is proposed that a defined frictional force between the inner and/or outer circumferential surface ( 36, 38 ) of the fastening element ( 22 ) and the adjacent component ( 10, 20, 32 ) is generated by an initial axial stress of the fastening element ( 22 ).

STATE OF THE ART

[0001] The invention starts from a fastening of a wiper system inaccordance with the pre-characterizing clause of claim 1.

[0002] Wiper systems for motor vehicles are fastened to the vehicle bodyof a motor vehicle with a wiper support, a so-called mounting plate or atubular mounting plate (if the wiper support contains elements of atube). The mounting plate includes a motor mounting plate, which carriesa wiper drive with a wiper motor and a gear built on it. Drive shafts ofthe windshield wiper are stored in wiper bearings, whose bearing housingis fastened to or formed on the ends of the mounting plate. The mountingplate is fastened to a vehicle body by screws via fastening eyes, whichare formed on the bearing housing, on the mounting plate and/or themotor mounting plate.

[0003] The end of the drive shaft projecting out of the vehicle bodyrepresents a considerable source of danger of injuries in the case ofaccidents with pedestrians. With respect to accidents with pedestrians,drafts of crash regulations from the European Commission (EC III/5021/96EN) define maximum acceleration values, so-called head injury criteria,in the area of the vehicle hood at the wiper system. These criteriacannot be met with standard wiper systems even if the vehicle hoodcovers the drive shaft, since even in this case there is no guaranteethat the distance between the vehicle hood and the drive shaft is largeenough, particularly in the case of small hood gaps.

[0004] One possibility for remedying this consists of the end of thedrive shaft giving way with an axial impact stress and being pushedaxially in its bearing into the engine compartment. A fastening of awiper system is known from EP 1 040 972 A2 in which the bearing housingof the drive shaft is connected to the vehicle body via an elasticelement and can be detached from the holder with an impact stress. Theelastic element is held positively engaged in a bearing eye next to thebearing housing via a ring groove. It is made of plastic with a Shorehardness of 60 to 70 and has a conical opening, which sits on a pinhaving a correspondingly conical circumference that is fastened to thevehicle body. In addition, the pin has a ring groove that has grooveflanks that are inclined towards the pin's longitudinal axis. Theelastic element engages positively in the groove with a correspondingprojection. In the case of an axial impact stress, the projection slidesout of the ring groove and the elastic element is pushed away from thepin so that the wiper system recedes into the vehicle body until itpushes against another part.

[0005] In one embodiment the elastic element is arranged directly on anopening in the body panel and is connected to this with positiveengagement. The pin sits fixed on the bearing housing as a hollow pin.In the case of an axial impact stress in the area of the drive shaft ofthe windshield wiper, the pin is pressed out of the elastic element,whereby the elastic element is compressed under the absorption of energyso that the bearing housing can recede until the windshield wiper isadjacent to the body panel. In both embodiments, the force required fordetachment can be varied by the geometric design of the pin and by theelastic material used.

[0006] A fastening for a tubular mounting plate is known from DE 198 33158 A1. According to this, a rubber elastic decoupling element isadapted to the inner contour of the mounting plate tube in the area ofthe fastening borehole. It projects through openings in the fasteningborehole with a projection and on the inside overlaps the opening in theaxial direction on both sides. The decoupling element is secured in theaxial and radial directions by positive engagement due to the projectionand the overlap. A spacer bush is used in the decoupling element tolimit the tension force of the fastening screws on the decouplingelement. The spacer bush comes to bear on the face according to apredetermined tension path and transmits the screw forces as far as theyexceed the desired initial stress.

ADVANTAGES OF THE INVENTION

[0007] According to the invention, a defined frictional force betweenthe inner and/or outer circumferential surface of the fastening elementand the adjacent component is generated by an initial axial stress ofthe fastening element. The frictional force is defined in such a waythat the mounting plate of a wiper system, which forms the adjacentcomponent, for example, is securely fastened on the vehicle body duringnormal operation. The connection between the vehicle body and themounting plate will only be detached when, in the case of an impact, thewiper system is stressed by an axially acting force that exceeds thedefined frictional force. The wiper system is displaced in the directionof the interior of the vehicle body in accordance with the requirementfor a lower risk of injury for persons outside the motor vehicle. Thefrictional force and thus the force acting against the impact can bedetermined very precisely by the extent of the initial stress.

[0008] Proven principles are used to fasten the wiper system so that thefastening points on the wiper system and the vehicle body can remain asthey are and no new construction is required. The rubber elastic andvibration-dampening fastening element sits with its outer circumferencein a receptacle opening, which as a rule is formed by a fastening eye onthe mounting plate. It has a central passage opening, which sits on afastening pin. This fastening pin is solidly connected to the vehiclebody. However, solutions are also possible where the receptacle openingof the vehicle body and the pin are assigned to the wiper system. Thefastening element is compressed axially during assembly, whereby itsdiameter enlarges and it is supported on the receptacle opening or onthe pin. The initial stress generates defined frictional forces on thecontact surfaces, which fix the wiper system on the vehicle body untilan axially acting force that exceeds the frictional force occurs. Theextent of the frictional force depends essentially on the initial stresspath, the material properties of the fastening element, its geometricdesign, its volume, and the relationship between the enclosed surface,the so-called loss surface, and the free surface.

[0009] According to an embodiment of the invention, with influencingfactors that are otherwise the same, the frictional force can becoordinated via the initial stress path, which is delimited by limitstops, e.g., a distance sleeve. In addition, the surfaces in contactwith each other between the fastening element, the fastening eye, andthe pin can run cylindrically or conically in one direction. In the caseof a cylindrical design, the initial stress generates a pressure forcewithout an axial force component, while, in the case of a conicalformation of the surfaces, depending upon the direction of the cone, itgenerates a force component in the direction of the axially actingholding force or in the opposite direction thereby increasing orlowering the axial force that is required to detach the fastening. Thepositively engaged connection achieved by the frictional force can alsobe supported by a positive engagement, e.g., in the form of variousholding protuberances on the fastening element or on the pin orfastening eye, which engage in corresponding recesses of the respectiveother adjacent part.

[0010] In one embodiment of the invention, the fastening element isarranged on the end of a fastening pin that is attached to the vehiclebody and features a ring groove in the center area. It is supported inthe direction of the axial force with the groove base on a bearingsurface, which is formed by the cylindrical receptacle opening of themounting plate. Since the diameter of the bearing surface is smallerthan the inside diameter of the ring groove, a frictional force existsbetween the fastening element and the mounting plate in this area. Thefrictional force is also defined via the volume and the coefficient offriction of the fastening element as well as a central sleeve, whichlimits the initial axial stress of the fastening element.

[0011] According to one embodiment of the invention, a contact disk isarranged beneath the fastening element. It can be used to vary the freesurface of the fastening element. The contact disk expediently featuresa predetermined breaking point, which breaks when a permissible axialforce is exceeded. The predetermined breaking point advantageously hasthe same diameter as the fastening pin so that the fastening element canyield axially. This reduces the enclosed surface of the fasteningelement and the pressure force on the frictional connection, which nowalso detaches under the effect of the axial force. Since the fasteningpin with the fastening element remains in place after the wiper systemis detached and therefore projects dangerously upwards, however, thisfastening possibility can only be used outside of a possible impactrange. If the fastening pin is arranged on the mounting plate and if itslides through the receptacle opening into the interior space of thevehicle body after the effect of an axial force, the fastening elementcan also be arranged in the impact range.

[0012] With another embodiment of the invention, a fastening element isprovided with an elastically deformable, hollow center area. With theeffect of an axial force, this fastening element first buckles in thecenter area, before, e.g., the frictional or positively engagedconnection detaches. The impact is thereby intercepted more smoothlywith a portion of the impact energy being annihilated. In addition, thefastening element advantageously absorbs smaller axial forces withoutthe fastening of the wiper system being detached.

[0013] All embodiments of the invention can be mounted simply andtherefore cost effectively. In addition, repair of the wiper systemafter an impact with a pedestrian is simple since the detachedcomponents only need to be re-mounted again.

DRAWINGS

[0014] Additional advantages are yielded from the following descriptionof the drawings. Exemplary embodiments of the invention are depicted inthe drawings. The drawings, the description and the claims containnumerous features in combination. The expert will also observeindividual features expediently and combine them into additional,meaningful combinations.

[0015] The drawings show:

[0016]FIG. 1 A perspective representation of a mounting plate of a wipersystem.

[0017]FIG. 2 A section through a fastening eye of a wiper system in amounted state.

[0018]FIGS. 3 and 4 Variations of FIG. 2.

[0019] FIGS. 5-7 Variations of a fastening element.

[0020] FIGS. 8-11 Variations of FIG. 2.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0021] A mounting plate 10 of a wiper system is comprised of a motormounting plate 12 and a mounting plate tube 14 (FIG. 1). While the motormounting plate 12 bears a wiper drive (not shown), wiper bearings 16 arearranged on the ends of the mounting plate tube 14. The mounting plate10 is fastened to a vehicle body 20 via fastening eyes 18, which areformed on the housings of the wiper bearings 16 and on the motormounting plate 12. The fastening eye 18 has a receptacle opening 26 fora rubber elastic fastening element 22, which simultaneously acts todampen vibration between the mounting plate 10 and the vehicle body 20(FIG. 2).

[0022] The fastening element 22 features a central passage opening 28for a fastening pin 32. This pin supports itself on one end with aformed collar 56 on a fore part 40 of the fastening element 22, whilethe other end is screwed onto the vehicle body 20 with the aid of screwnut 58. A sleeve 34 is arranged between the fastening pin 32 and thefastening element 22 and this sleeve limits the tension forces of thescrewed connection when it comes to bear on the face of the vehicle body20 in accordance with a predetermined tension path.

[0023] In an assembled state, the fastening element 22 is compressed andconforms with an inner circumferential surface 36 to the sleeve 34 andwith an outer circumferential surface 38 to the contour of thereceptacle opening 26 of the mounting plate 10. The circumference of thefastening element 22 enlarges due to initial axial stress so that apressure force and a frictional force are generated between the contactsurfaces, which forces fix the mounting plate 10 on the vehicle body. Ifan axial force 30 that exceeds the value of the frictional force occursin the case of an impact, the mounting plate 10 detaches from thefastening element 22.

[0024] The frictional force is adjusted via its influencing variables insuch a way that persons are not harmed by an accident. In the embodimentaccording to FIG. 2, the fastening element has an inner 36 and an outer38 circumferential surface running cylindrically. They are acted onperpendicularly by the pressure forces, which are generated by theinitial stress, so that no force components occur in the direction of anaxial force. In addition, the receptacle opening 26 has a holdingprotuberance 60 in the area of a fore part 40, and this protuberanceengages in the fastening element 22 thereby forming a positiveengagement that supports the frictional force. A formed-on collar 62 ofthe fastening element 22 serves to isolate front-side vibrations of themounting plate 10 vis-à-vis the vehicle body 20.

[0025] The outer circumferential surface 38 can also run conically,whereby the diameter either increases (FIG. 3) or decreases (FIG. 4) inthe direction of the vehicle body 20. An axial force component, whichacts against or supports the holding force, is generated by the initialstress in accordance with the angle of the cone. In addition, a holdingprotuberance 60 with a different design can be formed on, e.g., in aprojecting, rounded form (FIG. 5) or an angular recess. In addition, thefastening element 22 can be embodied as a truncated cone in the area ofthe fore part 40 (FIG. 6, FIG. 7). The shape variations can be combinedat will in order to define the frictional forces as precisely aspossible in accordance with the requirements and the given spaceconditions.

[0026] In the embodiment according to FIG. 8, the fastening element 22features a ring groove 42, which is supported on a bearing surface 44 inthe direction of the axial force 30. So that a frictional force isgenerated between the mounting plate 10 and the fastening element 22,the diameter of the bearing surface 44 is smaller than the insidediameter of the ring groove 42. In this embodiment, besides thecoefficient of friction and the volume of the fastening element 22, theextent of the frictional force is determined substantially by thedifference in diameter. The fastening element 22 is arranged on the endof the fastening pin 32 and is also supported on a contact disk 46 witha predetermined breaking point. If the axial force 30 exceeds apermissible value, the mounting plate 10 slips out of the ring groove42. At the same time, the contact disk 46 breaks at the predeterminedbreaking point and the mounting plate 10 slides along the fastening pin32 into the interior space of the vehicle body 20. The position of themounting plate 10 in this state is depicted in FIG. 8 by a dashed line.The fastening pin 32 with the fastening element 22 remains in place andprojects upwardly. As a result, it is expediently arranged outside apossible impact range of a person.

[0027] An alternative to this is depicted in FIG. 9. In this case, thefastening pin 32 is fastened to the mounting plate 10 and features afastening element 22 with a ring groove 42 on the end facing the vehiclebody 20. This element is supported with the groove base 54 on thebearing surface 44, which is formed by a cylindrical receptacle opening26 in the vehicle body 20. If the axial force 30 is greater than theholding force, the body panel 20 detaches from the ring groove 42 andthe fastening pin 32 slides in the receptacle opening 26 until adjacentcomponents of the mounting plate 10 meet at the vehicle body 20. Indoing so, the mounting plate 10 displaces in direction 48 and assumesthe position depicted by the dashed line, whereby the fastening element22 is pressed out of the receptacle opening.

[0028]FIG. 10 shows another embodiment according to which the fasteningelement 22 is connected to the mounting plate 10 at one end by atruncated conical clamp connection 50, while the other end features thering groove 42 that has already been described. Both ends are connectedvia a center area 52, which is hollow and elastically deformable. Thisarea absorbs axial forces first of all because of its elasticity. If theaxial force 30 continues to increase, it buckles more and more until thefastening element 22 releases from the vehicle body 20 when the axialforce 30 reaches a specific value and displaces against direction 48relative to the vehicle body, which is depicted in the figure by dashedlines.

[0029] Another embodiment (FIG. 11) is developed if the center area 52is combined with a central sleeve 34 and the ring groove 42 is alsoarranged in the center of the fastening element 22. The fasteningelement 22 features truncated conical ends in the area of the fore parts40, which are mounted against each other. Because of the initial axialstress, the center area 52 of the fastening element 22 deflectsoutwardly, the groove base 54 is pressed against the bearing surface 44of the receptacle opening 26, and the ends in the area of the fore parts40 are supported radially on the sleeve 34. After the effect of an axialforce 30 of a defined value, the fastening element 22 slides through thereceptacle opening 26, which can be formed via the mounting plate 10 orthe vehicle body 20.

1. Fastening of a wiper system (10) to a vehicle body (20) by means of arubber elastic fastening element (22), which sits on the circumferencein a receptacle opening (26) of the wiper system (10) or the vehiclebody (20) and sits with a passage opening (28) on a pin (32) of therespective other part, whereby the connection between the wiper system(10) and the vehicle body (20) is detachable via a defined axial force(30) in the direction of the interior of the vehicle body (20),characterized in that a defined frictional force between the innerand/or outer circumferential surface (36, 38) of the fastening element(22) and the adjacent component (10, 20, 32) is generated by an initialaxial stress of the fastening element (22).
 2. Fastening according toclaim 1, characterized in that a limit stop is provided, which limitsthe axial deformation of the fastening element (22) during assembly. 3.Fastening according to claim 2, characterized in that the limit stop isformed by a sleeve (34), which surrounds the fastening pin (32). 4.Fastening according to one of the preceding claims, characterized inthat the fastening element (22) with a conical inner or outercircumferential surface (36, 38) sits in the correspondingly designedreceptacle opening (26) or on the corresponding pin (32).
 5. Fasteningaccording to one of claims 1 through 3, characterized in that thecircumferential surfaces (36, 38) essentially run cylindrically. 6.Fastening according to one of the preceding claims, characterized inthat, in addition to adhesion, the fastening element (22) is held in thereceptacle opening (26) or on the pin (32) by an axially acting positiveengagement.
 7. Fastening according to one of the preceding claims,characterized in that one end of the fastening element (22) features atruncated conical fore part (40).
 8. Fastening according to one ofclaims 6 or 7, characterized in that the fastening element (22) featuresa ring groove (42) and is supported in the direction of the axial force(30) on a bearing surface (44), whose diameter is smaller than theinside diameter of the ring groove (42).
 9. Fastening according to oneof the preceding claims, characterized in that the fastening element(22) is supported in the direction of the axial force (30) on a contactdisk (46), which has a predetermined breaking point in accordance withthe permissible axial force (30).
 10. Fastening according to one of thepreceding claims, characterized in that the wiper system is fastened toa body panel of the vehicle body (20) from outside via a pin (32), andthe pin (32) is inserted into the body (20) with the occurrence of themaximum axial force (30).
 11. Fastening according to one of claims 1through 9, characterized in that the fastening element (22) is connectedon one end to the wiper system (24) via a truncated conical clampconnection (50) and is connected to the other end via an elasticallydeformable, hollow center area (52), which sits positively engaged inthe receptacle opening (26) via a ring groove (42).
 12. Fasteningaccording to one of the preceding claims, characterized in that thefastening element (22) features truncated conical fore parts (40) and,in the center area (52), a ring groove (42), whereby the center area(52) deflects to the outside due to the initial stress so that thegroove base (54) is pressed against the bearing position surface (44),while the ends are supported on the sleeve (34) in the area of the foreparts (40).